This is going to use the USER channel which does a lookup in your XML directory for <domain> the looks for <user> with the appropriate id within that domain.
once it finds one it will try to fetch the param dial-string from <params> in <user> or <domain> (in that order) once it finds that it tries to call it.
Clearly you have that misconfigured because it is not resolving it.
That is why my previous suggestion was to try the default config to compare.
mv /usr/local/freeswitch/conf /usr/local/freeswitch/conf.bak make install
The sample config uses the ip of the box as the domain and offers user 1000-1016 or something like that all with pass 1234.
Also, If you do not name your profile the same name as your domain or at least have an alias for the profile that is equal to your domain name you will not be able to use the user channel.
You can always opt for the alternate method of sofia/<profile name>/user%<domain>
Before I made the call I registered both phones manually (btw. I can
make calls from both phones).
Then I did a sofia status profile internal and it shows me both phones
registered on that domain: